I dont know what to do. I used to have 3 different shades of highlights before that needed to be refreshed. I put in it #6 Natural Instincts in Linen and it made my light blonde highlights turn dark and muddy like green! Nothing like the box! Why did this happen? I thought when ur hair is light, it will accept any color as long as it is on the same level. I left it on for 30 min maybe it was too long. I just want it fixed. Can I use a weak solution of bleach like 10v?

STEP AWAY FROM THE BLEACH! There's no need to bleach. You'll just damage your hair and possibly end up with some greenish-yellow or greenish-orange tones.

I use NI Linen on my highlights too. I think you're only supposed to leave it on for 15 minutes. If your hair is very porous, you should leave it on for less time. Do a test strand next time to see how much time your hair needs to process. The last time I used Natural Instincts I got a purplish tinge on my palest highlights. One wash with clarifying shampoo got rid of it. The good thing about NI is that it fades very quickly. Wash it a couple of times. I'm pretty sure the green will fade away.

If the green doesn't fade quickly enough, try a shampoo that's designed to warm up fading colours. Red counteracts green, so depositing a warm shade will correct the green. Something like Clairol Shimmer Lights Gold Conditioning Shampoo should do the trick. You could also use Roux Fanci-Full Mousse in Hidden Honey, Golden Spell or even Lucky Copper. These are purely temporary colours and won't damage your hair. You'll just have to use them until the NI fades. Good luck.

I know it's tempting to panic and dump something permanent on your hair, but it's really not necessary in this case.